Working with Multiple Layers

You have seen how to create, move, and remove layers, but the hour still hasn't really addressed the question of what they're good for. You will use layers in many situations. Whenever you are combining two or more images (in Photoshop terms, compositing), the elements you paste or drag in from another document over the background image are added on separate layers. You can use the Layers palette to control precisely how these elements are combined. You can control the opacity of objects you paste onto a layer or paint that you apply to it. (The layer itself is transparent, even if you set the paint on it to 100% opacity.) You can also control the blending modes that affect how one layer appears on top of another, just as you can when painting over an image or background.

Opacity

The Opacity slider at the top of the Layers palette controls the opacity of the active layer. You used it briefly earlier to change the opacity of the bacon. Make the slider appear by clicking the triangle to the right of the percentage window. It can be adjusted from 0%–100% by dragging the slider. If you'd rather not access the slider, enter a value by typing 0 for 100%, 1 for 10%, 2 for 20%, and so on. If you desire more precise control, simply type the digits of the measurement you desire (57, for instance) in quick succession. This trick works with any tool that doesn't have its own Opacity setting—with tools that do have Opacity settings, use the keyboard to adjust the setting for the tool rather than the layer.